Kepler-16b

Artist's concept

Kepler-16b was the Kepler telescope’s first discovery of a planet in a “circumbinary” orbit– circling two stars, as opposed to one star in a double-star system. Like Luke Skywalker's home planet Tatooine, Kepler-16b would have two sunsets if you could stand on its surface. This planet, however, is likely cold, about the size of Saturn and gaseous, though partly composed of rock. It lies outside its two stars’ “habitable zone,” where liquid water could exist. And its stars are cooler than our sun, probably rendering the planet lifeless. Of course, we could look on the bright side (so to speak). When the discovery was announced in 2011, Bill Borucki, the now-retired NASA principal investigator for Kepler at Ames Research Center, Moffett Field, California, said finding the new planet might actually broaden the prospects for life in our galaxy. About half of all stars belong to binary systems, so the fact that planets form around these, as well as around single stars, can only increase the odds.